On Wed, 30 Jun 2004 15:01:24 +0530, aksingh@hss.hns.com <aksingh@hss.hns.com> wrote: > > > so what are the differences between a kernel module and kernel threads they are _very_ different...to paraphrase from an old poem "a module is a module, a kernel_thread is a kernel_thread and never shall the twain meet !" i hope you meant, a 'kernel thread' and a 'userland process'. a kernel thread has no userspace context in it (as i said earlier, it's mm pointer is NULL etc.), they operate in kernel space _only_ > , as > you said kernel threads can be scheduled, pre-empted and all.that is one > Whats the utility of kernel threads, do drivers generally use them or if I > put it in a better way, when should someone think of using kernel threads > in his/her modules? i think you would use kernel threads in driver when you want to do something in a process context, not in a syscall. there must be bunch of kernel threads running on your system. for me, i have things like: pdflushd : responsible for writing dirty pages to disk. earlier this was done via the bdflush and kupdated. ksoftirqd: helps processing of softirqs to name a few. kind regards anupam > > thanks > Amit > > Anupam Kapoor <anupam.kapoor@gmail.com> on 06/30/2004 02:55:43 PM > > To: Jan Hudec <bulb@ucw.cz> > cc: Amit Kumar Singh/HSS@HSS, Anandraj <arm@tataelxsi.co.in>, > kernelnewbies@nl.linux.org > > Subject: Re: kernel threads > > > > > also, kernel threads have their mm pointer set to NULL. kernel threads > are schedulable, preemptible etc. just like normal processes. > > anupam > > On Wed, 30 Jun 2004 10:55:40 +0200, Jan Hudec <bulb@ucw.cz> wrote: > > On Wed, Jun 30, 2004 at 13:15:23 +0530, aksingh@hss.hns.com wrote: > > > i read that already, there the programmer has used his own functions to > > > create threads and all, i just wanted to know if kernel threads are > > > standard features and if kernel provides some functions to create, > destroy > > > them, because I never came across them in linux till now. I dont think > > > drivers create different threads, correct ? > > > > Kernel threads are created, surprisingly, with a function > > kernel_thread(). Then they need to call daemonize() to fully get rid of > > their userland and reparent to init, because they are created by cloning > > whatever process happens to be current. > > > > > ------------------------------------------------------------------------------- > > > Jan 'Bulb' Hudec > <bulb@ucw.cz> > > > > > > > > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
